NCT07636811 · Alnylam Pharmaceuticals
A Study to Evaluate Mivelsiran in Adult Participants With Early-Stage Down Syndrome-Associated Alzheimer's Disease (DS-AD)
What this study is about
The purpose of the study is to evaluate the effect of mivelsiran in adult participants with early-stage DS-AD and to characterize the safety, tolerability, and how the drug affects the body (PD) of mivelsiran.
View original scientific description
The purpose of the study is to evaluate the effect of mivelsiran in adult participants with early-stage DS-AD and to characterize the safety, tolerability, and pharmacodynamics (PD) of mivelsiran. The study will be conducted over 2 periods: a 24-month double-blind period and an optional 12-month open-label treatment extension (OLE) period. The estimated duration of study participation, inclusive of screening, treatment, and additional safety follow-up, is up to 39 months.
Interventions
DRUG
Mivelsiran
Mivelsiran will be administered intrathecally
DRUG
Placebo
Placebo will be administered intrathecally
Primary outcome measures
Double-Blind Period: Change from baseline in brain amyloid burden measured in centiloids (CLs)
Time frame: Up to 24 months
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Clinical diagnosis of Down-Syndrome (DS) associated with trisomy 21
- Positive amyloid PET scan
- Cognitively stable in the opinion of the investigator
- Seizures must be well controlled with no occurrence of seizures in the 6 months prior to screening
Exclusion criteria
- Has severe intellectual disability (ID)
- Has a history of DS regression disorder
- Has alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>2×upper limit of normal (ULN) at Screening
- Has estimated glomerular filtration rate (eGFR) \<45 mL/min/1.73m\^2 at Screening
- Has recently received an investigational agent
- Has had treatment with amyloid-targeting antibody
- Comorbidities such as obstructive sleep apnea and hypothyroidism that are not well controlled Note: other protocol defined inclusion / exclusion criteria apply
Where
- Maitland, Florida
- Naples, Florida
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 12, 2026 · Source of record for eligibility and locations